There are various types of gas grills or broilers on the market sold under a variety of brand names. The majority of these grills use a conventional port type gas burner that is manufactured in various configurations so that the products of combustion from the burning of the gas-air mixture provide the energy for cooking the food. In these types of grills, the heat transfer to the food is mostly by convection (hot air). Usually in these types of convective heat transfer grills, the burners are protected from liquids expelled from the food during the cooking process by some type of ceramic or metal covers placed over the burners. These covers or shields are heated to a level that will vaporize the juices expelled from the food during cooking. The vapors then pass over the food imparting a smoky flavor, sometimes referred to as an outdoor or “charbroiled” flavor. Some grill producers refer to these covers or shields as flavor-producing bars. In some publications and advertising, some of these types of grills are referred to as “radiant,” but in most instances, the amount of infrared radiant energy produced by a grill that does not employ a radiant type burner is negligible compared to the convective energy.
Another type of grill employs an infrared energy producing burner. A typical grill of this type is disclosed in U.S. Pat. Nos. 4,321,857 and 4,886,044 to Best. When the burner surface is open to the grids that support the food, the food is cooked with about one-half of the energy in the form of infrared radiant energy and the rest of the energy transferred to the food is in the form of convective heat. This type of infrared burner is described in U.S. Pat. Nos. 3,277,948 and 3,561,902 to Best. The third type of gas grill, described by U.S. Pat. No. 6,114,666 to Best, transfers all of the energy to the food in the form of infrared radiant energy. In this type of grill, the convective energy (products of combustion) from the combustion of the fuel-air mix is directed away from the food and is discharged without coming in contact with the food. In this type of gas grill, the food is broiled because it is cooked only by radiant energy.
One problem common to the prior art types of grills is flare-ups. When cooking, most flare-ups (uncontrolled burning) are caused when oils, discharged from the fat in the meat being cooked, ignite. The source of ignition for the oils is a hot surface or open flame with which the oils come in contact. The surface on which the oils fall is usually above the ignition temperature of the oils. In the early cycle of the cooking process, it is common practice to sear the meat, which requires high fire. On high fire, there is typically a source of ignition for these oils. Therefore, it is difficult to cook or broil meat containing fat fast enough to sear and mark the meat properly without causing flare-ups (causing excessive charring).
Flare-ups can be prevented by maintaining all surfaces of the grills with which the oils can come in contact at a temperature that is lower than the ignition temperature of the oils. However, these types of grills are designed for very slow cooking and are not usually used for cooking a variety of meat cuts such as steak, hamburgers, pork chops, and lamb chops. Also, these types of slow cooking grills are seldom used in commercial applications. Various marketing studies have shown that the primary use of consumer and commercial type grills is for cooking cuts of meat that are normally cooked or broiled relatively fast. For example, the time to cook or broil a 1 inch thick steak would be between 6 to 14 minutes, depending on how well done one likes a steak. A ⅓ pound hamburger should cook to a 160° F. center in less than 8 minutes. Most grills used in commercial applications must be capable of cooking or broiling meat relatively fast and to sear and mark the surface within 2 to 4 minutes.
The problems with flare-ups or uncontrolled burning are especially bothersome in commercial use because of the large quantities of meat being prepared at the same time. The larger cooking surfaces of these types of grills allow for more meat to be cooked or broiled at the same time, expelling more oil from the fat onto the grill creating the potential for large flare-ups. In the cooking of meats such as a 1 inch steak, it is highly desirable to sear and mark the surface quickly (2 to 4 minutes) and to complete the cooking or broiling in less than an additional 6 to 10 minutes. When conventional grills are heated to a level to accomplish the desired cooking times, flare-up becomes a constant problem if the meat contains even a moderate amount of fat.
Another problem typical of prior art types of grills is that the energy is not distributed uniformly over the cooking grid surface. A report published by Don Fisher of the Food Service Technology Center in San Ramon, Calif., Commercial Cooking Appliance Technology Assessment, Report No. 5011.02.26, clearly illustrates the variation in energy levels over the cooking grid surface. This report covers commercial types of grills, but the same problem exists with consumer types of grills. This particular problem with prior art types of grills impedes the cooking or broiling process and requires the chef to redistribute the food over the cooking grids in order to ensure energy absorption uniformity. Therefore, it is often difficult for even experienced chefs to cook or broil multiple pieces of meat to the same level of being done.
While flare-ups and poor heat distribution impose operational problems, typical prior art types of grills are also very inefficient. That is, a small amount of the energy consumed during operation is actually imparted to the food. This problem is discussed in the report mentioned above. The problem is less pronounced in the use of consumer grills because of briefer cooking periods. However, in commercial use this problem is more pronounced because many grills operate in excess of 12 hours each day. It is only logical to consume less energy to achieve the same or better results than it is to waste energy regardless of the application. The grill disclosed by U.S. Pat. No. 6,114,666 to Best has significantly increased the efficiency of gas grills over the prior art and provides the basis for still further improvement.
In the report referred to above published by the Food Service Technology Center, desirable characteristics of an advanced under-fired broiler or grill (to be developed in the future) are listed and include the following: improved uniformity, reduced energy consumption, reduced heat gain to the kitchen, lower emissions, and maintaining the signature “charbroiled” food characteristics. The report does not discuss flare-up as a problem. It is likely that flare-up is considered as a necessary evil of a hot grill. Considering the problems with existing prior art types grills, specifically related to flare-ups and energy distribution over the cooking grid surface, along with excessive energy consumption, it can be seen that a need exists for an improved grill or broiler that provides improvements with regard to one or more of the above-mentioned problems.